Consolidated Statements of Stockholders' Deficit (unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2016		68,399
Beginning balance at Dec. 31, 2016	$ (117,563)	$ 114	$ (1,725,349)	$ 922,687	$ 693,682	$ (8,697)
Increase (Decrease) in Stockholders' Equity
Comprehensive income	42,988				41,388	1,600
Dividend forfeitures on restricted stock	259				259
Restricted stock awards (in shares)		101
Restricted stock awards	0
Minimum tax withholding requirements (in shares)		(32)
Minimum tax withholding requirements	(247)			(247)
Stock-based compensation	2,709			2,709
Ending balance (in shares) at Jun. 30, 2017		68,468
Ending balance at Jun. 30, 2017	(71,854)	$ 114	(1,725,349)	925,149	735,329	(7,097)
Beginning balance (in shares) at Dec. 31, 2017		83,567
Beginning balance at Dec. 31, 2017	(185,921)	$ 130	(1,725,349)	1,001,315	543,814	(5,831)
Increase (Decrease) in Stockholders' Equity
Comprehensive income	16,573				19,531	(2,958)
Dividend forfeitures on restricted stock	42				42
Restricted stock awards (in shares)		378
Restricted stock awards	0
Minimum tax withholding requirements (in shares)		(57)
Minimum tax withholding requirements	(226)			(226)
Stock-based compensation	3,474			3,474
Ending balance (in shares) at Jun. 30, 2018		83,888
Ending balance at Jun. 30, 2018	$ (166,058)	$ 130	$ (1,725,349)	$ 1,004,563	$ 563,387	$ (8,789)